Calculation of Dosage from Radon Seeds

Abstract

In order to establish a system by which gamma ray intensity at distances from seeds may be related to depth doses from x-rays, radium tubes, and radium packs, on a common standard, for the use of radiologists in calculating tissue dosage, the following work has been attempted. In the past it has been customary at the State Institute, when calculating tissue dosage from seeds, to multiply the total milli-curie hours contributed by the seeds by a factor, in order to obtain the intensity (in per cent) of a skin erythema dose at a point 3 cm. distant from the center of the mass which was seeded. The 3 cm. distance was chosen because originally a large percentage of the cases where seeding and external radiation were combined, were uterine, and the average distance from the seeded area to the intestine and Madder was 3 cm. The use of the factor .03 has been reported by Mattick and Stenstrom (1) and by Mattick (2). It is often essential however, to determine the intensity at greater distances than 3 cm. from the seeded area, especially when tubes and radium packs or tubes and high-power x-rays are used in addition to seeds, and to be able to correlate this intensity with our standard skin erythema dose.